Sinnoh Starters

Now, I will tell you about the starter pokemon of Sinnoh. In this game, you  can also choose between three pokemon Professor Rowan shows you. I'll tell you something, there is no such thing as the strongest among those three. They just have their own advantages against the others. Let's begin.

Piplup-Prinplup-Empoleon

1. Piplup
 Piplup is the little cute blue penguin pokemon Dawn owns in the Pokemon Diamond & Pearl show. Piplup is the water type starter of this series. It learns bubble as its first water-type move. It has the appearance of a little blue penguin and happy-go-lucky personality. Piplup has the quite balanced stats. If you are a beginner in this, Piplup is your best shot because the first gym you'll face is the rock-type gym which Roark leads and your Piplup will strike Roark's pokemon to nothing. Besides Empoleon's Water-Steel type is quite a thing.
Piplup evolves into Prinplup at level 17, which evolves into Empoleon, a Water-Steel type pokemon at level 36.

Chimchar-Monferno-Infernape

2. Chimchar

Chimchar is the small monkey pokemon. Chimchar is the fire-type starter in this series. Chimchar is owned by a trainer named Paul in Pokemon Diamond & Pearl show but then Paul abandoned Chimchar later on because he thinks Chimchar is not strong enough to be with him. Chimchar is then asked by Ash to start a journey with him after Paul abandoned it. Flint, one of the Elite Four owns an Infernape in the series. Chimchar knows Ember as its first fire-type move. Chimchar has quite good Speed and Sp. Attack stats. Monferno's Fight type can punch the Normal types into oblivion. So you don't have to catch a Fight type on the go if you don't want to catch one. Chimchar evolves into Monferno, a Fire-Fight type pokemon, at level 14, which evolves into Infernape at level 36.

3. Turtwig

Turtwig-Grotle-Torterra

Turtwig has the appearance of a little turtle with a couple of leaves on a little twig on its head. Turtwig is the grass-type starter in the series. Ash owns a Turtwig in Pokemon Diamond & Pearl series. Later on in the series Gardenia, the gym-leader of Eterna City which is a grass-type gym, is known also owns a Turtwig. Even if it's a little slow, Turtwig has a good defense stat. If you want a good defense in a pokemon,Turtwig is your best choice.Turtwig evolves into Grotle at level 18 which evolves into Torterra, a Grass-Ground type pokemon, at level 32.

Sinnoh's starters

source : game experience, Serebii Pokedex, Bulbapedia Pokedex